Multiple explosive, line charge, package



1967 c. A. AXELSON ETAL 3,3

MULTIPLE EXPLOSIVE, LINE CHARGE, PACKAGE Filed Oct. 24, 1966 4 Sheets-Sheet 1 Carl A. Axelson Elton -Y. McGann John H. Smith 23, 1967 c. A. AXELSON ETAL 3,

MULTIPLE EXPLOSIVE, LINE CHARGE, PACKAGE Filed Oct. 24, 1966 4 Sheets-Sheet 2 f W I GUT CUT '- CUT DETON ATOR Nov. 28, 1967 c. A. AXELSON ETAL. 3,354,826

MULTIPLE EXPLOSIVE, LINE CHARGE, PACKAGE Filed Oct. 24, 1966 4 Sheets$heet 5 A M w w r A G a M 3 m .P 3 3 J fl -1 a Iv fi \W m 7 2 w m w n 0 m" w 8 I 8 F 3 3 .IID ,LQT E 0 mg m Nov. 28, 1967 c. A. AXELSON ETAL 3,354,326

MULTIPLE EXPLOSIVE, LINE CHARGE, PACKAGE FIG. 9

United States Patent 3,354,826 MULTIPLE EXPLOSIVE, LINE CHARGE, PACKAGE Carl A. Axelson, Beverly, Mass., and Elton Y. McGann,

Williamsburg, and John H. Smith, Seaford, Va., as-

signors to the United States of America as represented by the Secretary of the Navy Filed Oct. 24, 1966, Ser. No. 589,138 Claims. (Cl. 102-22) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates generally to explosive charges and more particularly to an underwater explosive charge suitable for echo ranging.

In the use of underwater explosives for echo ranging systems, it is desirable to obtain an optimum acoustic pattern in which surface and bottom reverberations are reduced to a minimum. Generally the shock waves pro duced by underwater explosives are spherical in pattern, producing shock waves having magnitudes as great in the vertical direction as in the horizontal direction. As a result, it is difficult to discriminate between echoes caused by vertical reflections from the surface and bottom of a body of water and those caused by horizontal reflections from a target, such as a submarine.

It has been demonstrated that an explosive charge formed from a strip of explosive material, as provided in the instant invention, in which the length of the explosive material is several times the width thereof, shock waves are produced which have much greater intensity in the horizontal direction than in the vertical. Because of the more favorable ratio between the magnitudes of the horizontal and vertical shock waves, discrimination between shock waves reflected from a target and shock waves reflected from surface and bottom reflections is greatly enhanced.

An object of this invention is to provide an underwater explosive having directional shock Waves characteristics.

Another object of this invention is to provide an underwater explosive in which surface and bottom reverberations have been reduced to improve echo ranging operations.

A further object of this invention is to provide an articulated foldable strip of explosive material which may be vertically deployed in a body of water.

A still further object of this invention is to provide an articulated foldable explosive line charge assembly which may be packaged into a multiple number of line charge assemblies for deployment and detonation.

According to the present invention, the foregoing and other objects are attained by an explosive line charge which is made up of an explosive strip folded into a stack to form a part of a multiple explosive charge package which may be dropped into water and each line charge deployed and detonated separately.

A more complete appreciation of the invention and many of its attendant advantages will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 illustrates an echo ranging system;

FIG. 2 is a perspective view of an articulated line charge;

FIG. 3 is a cross section taken through the folded articulated line charge;

FIG. 4 is an exploded view, partly in section, of the elements of the line charge;

FIG. 5 is a view of the end disc securing block;

3,354,826 Patented Nov. 28, 1967 FIG. 6 is a cross sectional view of the end disc and securing block;

FIG. 7 is an exploded edge view of the disc assembly;

FIG. 8 is a cross sectional view of an arming mechanism;

FIG. 9 is a side view of an actuation mechanism for use in the arming mechanism; and

FIG. 10 illustrates a line charge folded into a stack as part of a multiple explosive package.

Referring to FIG. 1, an aircraft 7 is illustrated transmitting a signal to a floatation unit 8 which may include an antenna, a radio receiver and -a switching device such as a stepping switch, not shown, a cable 9 extends between the flotation unit and a multiple explosive package 10 according to this invention. Cable 9 provides electrical and mechanical connections between the floatation unit and the multiple explosive package. The individual line charges of the multiple explosive package 10 are formed of a plurality of individual explosive strips 11 as more clearly shown in FIG. 2.

Explosive strip 11 is formed of a product of the DuPont Company, known in the art as Detasheet. The strip is trimmed into a plurality of octagon shaped discs 12 joined at their common sides 13. The nature of the explosive is such that the common sides will fracture along the line of the bend upon the strip being folded. A central horizontal slit 14 is formed in each octagon through which i a tape 15 is threaded. The tape is held in tension. As more clearly shown in FIGS. 3 and 4, strips 16 and 17, which may be made of a plastic material known in the art as Mylar, are adhesively affixed to each face of the explosive strip. These strips serve to hold the tape in a tensed condition which in turn holds the individual octagons in contact at their common side, the Mylar strips and the tape serving as hinges and permitting the folding of the octagons one upon the other. a

As shown in FIG. 2, tape 15 extends beyond the explosive strip and is attached at its bottom end to an arming and detonating mechanism 18. To ensure contact bet-ween the detonating mechanism and the explosive strip, a special attaching fixture 19, shown in FIG. 5, is used to attach the arming and detonating mechanism to the explosive strip. This special fixture is attached to the arming mechanism by a pair of bolts 21. The tape is threaded through a central hole in fixture 19 and folded over to receive a pin 22 through its looped end. The tightening of the bolts 21 prevents the withdrawal of the tape. Along with the tape, a tabbed end 23 of the lowermost octagon is also threaded through the hole in the fixture and wedged in place by small pieces of explosive to insure close contact with a relay or explosive lead out 24. As shown in FIG. 6, relay 24 contacts the ends of the explosive strip and contains a powder train 25 which is separated from the end of the explosive strip by a thin Wall 26. Upon detonation of powder train 25, this wall is ruptured and the explosive strip 11 ignited.

The upper end of tape 15 is secured to a disc or drag plate 27 (FIG. 1) in such a way that the disc is supported in a position normal to the length of the strip to impede movement of the explosive strip 11 downward through the water thereby resulting in the strip becoming vertically disposed when in the water.

The method of making the explosive strip 11 may be described as follows:

The explosive material is purchased in strip form, having a width about thirty (30) times its thickness and is cut into lengths about 20 times its width. It is then cut to provide a plurality of slits located along the longitudinal center of the strip, and a nylon tape is threaded through the slits, appearing first on one face of the strip and then on the other, for a distance equal to the space between the slits. The nylon tape is stretched and while under tension the Mylar facing strips 16 and 17 are ad hesively secured to each face of the strip. This holds the nylon tape under tension and exerts stress on the explosive tape clue to the elasticity of the nylon tape. The explosive strip with the nylon tape and the Mylar facing strips is then cut into a plurality of octagonal sections by placing it in a die. The die is also used to cut the Mylar facing into sections equal in length to two of the octagonal sections. This cutting is done first on one face and then on the other, the depth of the cut being such that only one face of the Mylar and part of the thickness of the explosive material is severed. The cuts through the Mylar facing strips are alternated on the two faces so that the cuts are never in line, the cut on one face being opposite to the center of the Mylar section on the other face, as shown in FIG. 7.

The strip is then folded, the folds being along the common side of the octagonal sections and the retardation disc or drag plate is attached to the upper end of the strip. This disc is attached to the extended end of the nylon tape in such a manner that the surface is at right angles to the longitudinal center line of the strip.

In FIG. 8, the arming and detonating mechanism 18 used with the explosive line charge 11 is shown as having a brass body 101 which houses an arming piston 102. Piston 102 is slideable within a chamber 103 and in the armed position, as illustrated, forms an explosive barrier between the explosive relay 24 and a delay detonator 104. Arming piston 102 is held in the unarmed position by an arming pin 105. A safety wire 106, which encircles body 101, keeps arming pin 105 in place. A safety wire 106 is also laced through two holes in an actuator mechanism body 107 which houses the delay detonator 104. Two O-rings 108 and 109 provide seals which prevent seawater entry into chamber or cavity 103. A washer 110 and a sleeve 111 serve as O-ring positioners and are staked in place in body 101.

Body 101 has a cavity 112 therein which provides space for venting expanding gases created by the burning of delay detonator 104. Cavity 112 is closed by a plug 113 and sealed against sea water entry by an O-ring 114. An O-rin-g seals cavity 112 from cylindrical chamber 103.

The actuator mechanism assembly of FIG. 8 is more clearly shown in FIG. 9 as having stab type delay detonator 104 crimped in place within the actuator mechanism body or delay detonator housing 107. A firing pin 116 is slideably disposed within a sleeve 117. A tape disc 118 provides a seal for a propellant charge 119. An electrical ignition assembly 120 is located adjacent to the propellant charge for igniting the charge. An epoxy resin 121 is used for sealing the ignition assembly in place. A squib holder body 122 is provided for holding the squib assembly in place within the actuator body 107. The squib holder body 122 is provided with a 360 knife edge at the outer end thereof for the purpose of cutting electrical leads 123 after detonation occurs. O-rings 124, 125, 126 and 127 in the actuator mechanism body 107 provide for sealing the actuator mechanism from sea water. Electrical leads 123 connect the ignition assembly to the floatation unit so that detonation may be initiated.

In FIG. 10, the explosive line charge 11 is shown assembled with a drag plate 27 and the octagonal discs 12 folded into a stack between two arming and firing mechanisms 18 and 18A, the stack being held together by spacer rods 126. Safety wires 106 and 106A are employed to hold the spacer rods in place. Electrical leads 123 and 123A connect to the floatation unit 8 of FIG. 1. One of the arming mechanisms (18A) is part of an adjacent explosive line charge of a multiple charge package 10.

In operation, a signal received by the radio in the floatation unit 8 is applied through a switching means and electrical leads 123 to the electrical ignition assembly 120, causing the propellant charge 119 to ignite. Gas pressure generated by the burning propellant charge imparts a velocity to firing pin 116 and causes squib holder 104 to be ejected from the actuator. The 360 knife edge of the squib holder cuts the electrical leads 123 and the safety wire 106, freeing the idividual line charge for deployment and detonation. With safety wire 106 removed, arming pin is free to move and hydrostatic pressure now forces piston 102 upward until the hole therein is in line with the detonator 104. Detonator 104 having been detonated by firing pin 116 creates an explosion which spans the air gap now present between the detonator and explosive lead out 24. Ignition of the explosive lead out in turn causes ignition of the explosive material of the individual line charge thereby generating a shock wave having a greater intensity in the horizontal than the vertical plane. The delay provided by the delay detonator allows time for separation, arming, and deployment of the individual line charge into a vertically disposed position in the water. Actuation of the remaining line charges is accomplished in a similar manner.

Obviously many modifications and variations are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A foldable articulated explosive strip adapted to be exploded underwater in a vertical line position, comprising:

a plurality of discs arranged in a line; resilient means passing through the approximate center of each of the discs and holding each disc in contacting relation with its adjacent disc, said resilient means being tensed and extending beyond said strip at each end; means adhesively affixed to each face of the discs and holding the resilient means in tensed condition, said adhesively attached means being in sections extending the distance to two discs, said sections being oppositely staggered with relation to each other to provide continuous attachment of the discs by means of the adhesive sections, throughout the length of the strip; means attached to one end of the resilient means threaded through the discs to detonate said strip; and

means attached to the other end of said resilient means to serve as a deterent to descent of the strip through the water and to extend the strip to a vertical line position.

2. A foldable articulated explosive strip adapted to be exploded underwater and in a vertical line position according to claim 1 wherein the means adhesively afiixed to each face of the discs comprises a Mylar strip, and said strip being cut into sections of two adjacent discs and affixed to opposite faces of the strip so that the end of the section on one face is opposite to the middle line of the section affixed to the opposite face of the strip.

3. A method of forming a foldable articulated explosive strip, adapted to be exploded underwater in an extended position. comprising:

selecting a strip of explosive material approximately twenty (20) times as long as wide and of a thick ness of less than one-thirtieth of the width;

cutting a plurality of lateral slits in said strip, said slits being located on the longitudinal center and evenly spaced throughout the length of the strip;

threading a resilient tape through said slits, said tape extending beyond said strip at each end and adapted to serve as a supporting tape when said strip is in extended position;

tensing said tape;

applying a strip of plastic material adhesively to each side of the taped strip holding the tape in tensed condition;

cutting said strip along its linear edges to form a plurality of discs, each having one of the slits at its center, and joined to an adjacent disc along their common side;

severing the plastic strip at intervals and at the juncture of adjacent discs on the side Opposite to the exposed tape, forming plastic sections of the length of two discs alternately forming hinges on opposite sides of the strips, the tensed tape serving also as hinges and as means insuring contact along the common side of the adjacent discs;

forming one of the end discs with a tab extending from its free end and in line with said strip; aifixing a means for detonating said explosive strip to said tab and said extended supporting tape, said means serving as a weight to pull said strip from folded position to an extended position; and

attaching a retarding means to the free end of said supporting tape to provide a deterent for the strip in its descent.

4. A method of forming a foldable articulated explosive strip according to claim 3 wherein the cutting along the linear edges forms six sides of an octagon shaped disc.

5. A multiple explosive charge package comprising,

a plurality of individual line charges, each of said line charges being formed of a strip of explosive material folded into a stack, of arming and detonating means connected to the lower end of each of said line charges whereby each of said line charges may be deployed and detonated, and

disc means connected to the upper end of each of said line charge for retarding the descent of the associated line charge through a body of water.

References Cited UNITED STATES PATENTS 3,006,279 10/1961 Lawrence 102-22 3,076,408 2/1963 Poulter et al. 10223 3,169,478 2/1965 Schaaf 10222 3,242,862 3/1966 Stegbeck et a1. 10222 BENJAMIN A. BORCHELT, Primary Examiner.

V. R. PENDEGRASS, Assistant Examiner. 

1. A FOLDABLE ARTICULATED EXPOLSIVE STRIP ADAPTED TO BE EXPLODED UNDERWATER IN A VERTICAL LINE POSITION, COMPRISING: A PLURALITY OF DISCS ARRANGED IN A LINE; RESILIENT MEANS PASSING THROUGH THE APPROXIMATE CENTER OF EACH OF THE DISCS AND HOLDING EACH DISC IN CONTACTING RELATION WITH ITS ADJACENT DISC, SAID RESILIENT MEANS BEING TENSED AND EXTENDING BEYOND SAID STRIP AT EACH END; MEANS ADHESIVELY AFFIXED TOEACH FACE OF THE DISCS AND HOLDING THE RESILIENT MEANS IN TENSED CONDITION, SAID ADHESIVELY ATTACHED MEANS BEING IN SECTIONS EXTENDING THE DISTANCE TO TWO DISCS, SAID SECTIONS BEING OPPOSITELY STAGGERED WITH RELATION TO EACH OTHER TO PROVIDE CONTINOUS ATTACHMENT OF THE DISCS BY MEANS OF THE ADHESIVE SECTIONS, THROUGHOUT THE LENGTH OF THE STRIP; MEANS ATTACHED TO ONE END OF THE RESILIENT MEANS THREADED THROUGH THE DISCS TO DETONATE SAID STRIP; AND MEANS ATTACHED TO THE OTHER END OF SAID RESILIENT MEANS TO SERVE AS A DETERENT TO DESCENT OF THE STRIP THROUGH THE WATER AND TO EXTEND THE STRIP TO A VERTICAL LINE POSITION. 